1. THE FIELD OF THE INVENTION
This invention relates to air deflecting devices and more particularly to that class of portable apparatus adapted to be mounted to the roof of a towing vehicle.
2. DESCRIPTION OF THE PRIOR ART
The prior art abounds with towing vehicle borne air deflectors utilized to diminish the drag effect incurred by towed vehicles. U.S. Pat. No. 3,794,372 issued on Feb. 26, 1974 to W. Webb teaches an air deflector mounted on the roof of a towing vehicle to deflect air upwardly and sideways relative to a trailer, thereby decreasing the drag of the trailer. The air deflector inclines rearwardly and upwardly from a front edge which rests sealingly on the roof of the towing vehicle as close as possible to the top of the windshield, the deflector widening rearwardly and having depending side surfaces, with means extending between the roof and the deflector for varying the inclination of the deflector.
U.S. Pat. No. 3,596,974 issued on Aug. 3, 1971 to J. Q. Adams discloses an air current deflecting device for use with a vehicle pulling a trailer or the like. An elongated transparent deflecting shield is pivotably secured to a pair of spaced apart support members which are detachably secured to the vehicle so as to position the deflecting shield above the roof of the vehicle. The shield includes a face portion having a length approximately equal to the width of the vehicle roof and having wing portions at opposite ends thereof which extend downwardly and rearwardly therefrom. The shield is selectively movable from a position wherein the leading edge of the face portion is positioned below and forwardly of the trailing edge of the face portion so that the inclined face portion will deflect air currents passing over the vehicle roof upwardly and rearwardly above the forward end of the trailer. The lower or leading edge of the shield is positioned above the vehicle roof to permit a certain amount of air to pass therebelow to eliminate the formation of a vacuum pocket rearwardly of the shield means. The shield may also be selectively pivoted to an inoperative position wherein the face portion of the shield is substantially parallel to the roof of the vehicle.
Both of the aforementioned inventions suffer the common deficiency of providing fixed dimensioned side air deflectors affixed to the side edges of the inclined deflecting surface. Such apparatus is susceptible to gusts of air directed to the side of the towing vehicle causing the air deflecting characteristics of such apparatus to be ineffective and, in some instances, causing an upwardly directed force to be exerted upon the lowermost surface of the inclined deflecting surface.